OBJECTIVE LENS, ELECTRON MICROSCOPE, OBJECTIVE LENS CLEANING METHOD, AND JIG

To provide an objective lens capable of easily removing foreign matter in the objective lens.SOLUTION: An objective lens 100 includes an objective lens body 2, and an electrode 150 that can be attached to and detached from the objective lens body 2. The objective lens body 2 includes an outer yoke 110, an inner yoke 120 arranged inside the outer yoke 110, and a nut 160 that removably holds an electric field ring 150. The electric field ring 150 is arranged at the tip of the inner yoke 120, and the electric field ring 150 includes a threaded portion 152 held by the nut 160 and a shat portion 154 fitted to a fitting hole 112 provided in the objective lens body 2. The fit of the fitting hole 112 and the shaft portion 154 regulates the coaxiality between the electric field ring 150 and the objective lens body 2.SELECTED DRAWING: Figure 3 【課題】対物レンズ内の異物を容易に除去できる対物レンズを提供する。【解決手段】対物レンズ１００は、対物レンズ本体２と、対物レンズ本体２に着脱可能な電極１５０と、を含み、対物レンズ本体２は、外ヨーク１１０と、外ヨーク１１０内に配置された内ヨーク１２０と、電界リング１５０を着脱可能に保持するナット１６０と、を含み、電界リング１５０は、内ヨーク１２０の先端に配置され、電界リング１５０は、ナット１６０で保持されるねじ部１５２と、対物レンズ本体２に設けられた嵌合孔１１２にはめあわされる軸部１５４と、を含み、嵌合孔１１２と軸部１５４のはめあいによって、電界リング１５０と対物レンズ本体２の同軸度が規制される。【選択図】図３